#define _CRT_SECURE_NO_WARNINGS 1
#include<iostream>
using namespace std;
void swap(int& x, int& y)
{
	int t = x;
	x = y;
	y = t;
}
int main()
{
	int a = 3, b = 5, c = 10, d = 20;
	cout << "a=" << a << " b=" << b << endl;
	swap(a, b);
	cout << "a=" << a << " b=" << b << endl;
	cout << "c=" << c << " d=" << d << endl;
	swap(c, d);
	cout << "c=" << c << " d=" << d << endl;
	return 0;
}